Salient features of a parallel programmable interface-8255, Computer Engineering

Assignment Help:

Determine the salient features of a parallel programmable interface, 8255.

  • 24 I/O lines in 3 8-bit port groups - A, B, C
  • A, B can be 8-bit input or output ports
  • C can serve as 2 4-bit input or output ports
  • 3 modes of operation:

- Mode 0: A, B, C simple input or output level sensitive ports

- Mode 1: A, B input or output ports with strobe control in C

- Mode 2: A is bidirectional with control/handshake in B and C

  • A, B can only change 1 byte at a time
  • C has individual bit set/reset capability
  • Advantage is non-dedicated circuit can change port configuration with software and no 'glue logic'
  • Ports A, B, and C are used for I/O data.
  • The control register is programmed to select the operation mode of the three ports A, B, and C.
  • Mode0: simple I/O mode
  • Any of the ports A, B, CL and CU can be programmed as input or output.
  • No control of individual bits (all bits are out or all bits are in)
  • Mode 1: Ports A and B can be used as input or output ports with handshaking.
  • Mode2: Port A can be used as bidirectional I/O port with handshaking

 


Related Discussions:- Salient features of a parallel programmable interface-8255

List factors that determine the storage device performance, List the factor...

List the factors that determine the storage device performance. i.Access time ii.Cycle time iii.Transfer Rate.

Explain basic working of mainframes, Q. Explain Basic working of Mainframes...

Q. Explain Basic working of Mainframes? Mainframe computers are normally 32-bit machines or higher. These are suited to large organizations, to manage high volume applications.

Describe the hardwired control method, Describe the Hardwired control metho...

Describe the Hardwired control method for generating the control signals Hard-wired control can be explained as sequential logic circuit that generates particular sequences of

Explain tri-state logic inverter, Explain Tri-state logic inverter with the...

Explain Tri-state logic inverter with the help of a circuit diagram. Give its Truth Table. Ans: Tri-state Logic Inverter: The functional diagram of Tri-state Logic Inve

How semaphores implement mutual exclusion, How semaphores implement mutual ...

How semaphores implement mutual exclusion? Mutual-exclusion implementation along with semaphores: Assume that there are n-processes and they share a semaphore, mutex (stan

Use of arrays in assembly, An array is referencing using a base array value...

An array is referencing using a base array value as well as an index. To simplify addressing in arrays 8086 has provided two index registers for mathematical computations viz. BP a

How to join to mwseries from power builder 8.0, Using CICS Transaction Gate...

Using CICS Transaction Gateway we can join MQ Series with Power Builder 8.0

Structured analysis and design approach, Q. Structured Analysis and Design ...

Q. Structured Analysis and Design Approach? The objective of structured system analysis and design is to reduce maintenance time as well as effort. Modeling is the act of drawi

What is a spool request, What is a Spool request? Spool requests are f...

What is a Spool request? Spool requests are formed during dialog or background processing and placed in the spool database with information about the printer and print format.

Describe the basic aspects of ENIAC, Q. Describe the basic aspects of ENIAC...

Q. Describe the basic aspects of ENIAC? The main aspects of ENIAC can be summarized as: ENIAC was a general purpose-computing machine in that vacuum tube technology was

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd